Javascript event keypress returns invalid value with uncased

I found that keypress is not returning the correct charCode value. http://jsfiddle.net/cheonhyang/t9hL1k1n/

HTML:

<h1> keydown, keyup and keypress event</h1>
<input id="input"></input>

      

        
        
        
      

    

JS:

var input = document.getElementById('input');
input.addEventListener('keydown', function(e){
    console.log("input keydown");
     console.log("which: " + e.which);
    console.log("keyCode: " + e.keyCode);
    console.log("charCode: " + e.charCode);

});
input.addEventListener('keyup', function(e){
    console.log("input keyup");
     console.log("which: " + e.which);
    console.log("keyCode: " + e.keyCode);
    console.log("charCode: " + e.charCode);
});
input.addEventListener('keypress', function(e){
    console.log("input keypress");
     console.log("which: " + e.which);
    console.log("keyCode: " + e.keyCode);
    console.log("charCode: " + e.charCode);
});

      

        
        
        
      

    

When "a" is pressed, charCode returns "A", and when "A" is pressed, charCode returns "a".

It is very strange.

Typing "a" will result in:

keydown input which are: 65 keyCode: 65 charCode: 0

keystroke which: 97 keyCode: 97 charCode: 97

input keyboard which are: 65 keyCode: 65 charCode: 0